On May 9, 2025, the FIA ​​announced a bombshell finding following an intensive investigation into McLaren’s rear brake design, spearheaded by Red Bull’s Christian Horner, confirming that McLaren had used an illegal method to monitor rear tire temperatures. The revelation, centered on a secret water-cooling system within the MCL39’s brake drums, has rocked Formula 1, casting a shadow over McLaren’s dominant 2025 season and sparking heated debate over ethics, innovation and regulatory enforcement in the sport.

McLaren’s early season supremacy, with five wins in six races including a 1-2 finish at the Miami Grand Prix, drew scrutiny for its exceptional tire management. Rivals, notably Red Bull, noted McLaren’s ability to keep Pirelli tires in optimal temperature windows, particularly in hot conditions such as Bahrain and Miami, where Oscar Piastri and Lando Norris outpaced rivals by more than 30 seconds. Horner, Red Bull’s team principle, spearheaded suspicions, alleging that McLaren was using water to cool the tires – a practice banned under F1’s technical regulations. Auto Motor UND Sport reported Red Bull’s use of thermal imaging cameras, which revealed unusually cool “blue spots” on McLaren’s rear brake drums, in contrast to the orange and red hues of other teams’ setups, suggesting an unnatural cooling mechanism.

The FIA’s investigation, intensified after Miami, discovered a sophisticated system within McLaren’s brake ducts that injected minute amounts of water to regulate tire temperatures. According to planetf1.com, this system exploited a loophole by channeling water through the brake cooling shafts, indirectly cooling the wheel rims and tires without directly injecting it into the Pirelli rubber – a previously banned method. The FIA’s post-Miami inspection, detailed through the race, confirmed the presence of this illegal mechanism, leading to a formal ruling that McLaren’s design violated article 3.13 of the technical regulations, which prohibits any liquid tire cooling.

McLaren Team Principal Andrea Stella initially defended the team’s engineering and praised their “Mastery of the Black Art” of tire management in a Motorsport.com interview on May 7. CEO Zak Brown humorously dismissed earlier allegations, sipping from a “tyre water” bottle during Miami, and challenging rivals to protest. However, the FIA’s findings contradicted McLaren’s claims of compliance, finding that the team had deliberately operated in a regulatory gray area. The governing body issued a directive requiring McLaren to dismantle the system ahead of the Emilia Romagna Grand Prix, with potential fines, including points deductions, under review.

The fallout has polarized the paddock. Horner, speaking to ESPN on May 7, stopped short of accusing McLaren of outright cheating but stressed that leading teams face intense scrutiny, citing Red Bull’s own battles with allegations into 2024. Mercedes’ Tottenham Wolff, in a May 6 F1-Fansite.com interview, had previously defended McLaren, saying their advantage was “completely legit.” Wolff acknowledged the need for rivals to “work their way out” of McLaren’s shadow post-ruling, but the FIA’s ruling has shifted sentiment. Posts on X, such as @BrakeBoosted’s May 3 claim of Red Bull’s thermal imaging evidence, reflect fan outrage, with some calling McLaren’s actions “a disgrace” while others argue it was “clever engineering” caught by the rules.

The implications of the scandal extend beyond McLaren. Red Bull, 105 points behind in the constructors’ championship, stands to gain if fines are imposed, though Horner denied pushing for protests, per the sports mole. The FIA ​​is facing pressure to tighten regulations, with Pirelli’s Mario Isola noting on November 3, 2024, via Planetf1.com that detecting such tricks is challenging due to their subtlety. The controversy also highlights the cutthroat nature of F1, where innovation often runs afoul of legality, as seen in Red Bull’s 2024 Bib regulator and McLaren’s mini-DRS wing sagas, both cleared up by the FIA.

McLaren’s dominance, driven by Piastri and Norris, now hangs in the balance. The team’s 77-point constructors’ standings and Piastri’s leading edge as drivers could be threatened if retrospective penalties are applied. Rivals including Ferrari and Mercedes are racing to replicate McLaren’s legal tyre management techniques ahead of the 2026 overhaul. As the paddock heads to Imola, the FIA’s ruling has redefined the 2025 narrative, exposing McLaren’s illegal lead and reigniting debates over how far teams can push F1’s technical boundaries.